Furnace



Febo 5 y E924. M4825@ T. A. MARSH v FURNACE Filed Feb. 25 192;

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THOMAS A. MARSH, F CHICAGO, ILLINOIS, ASSIG-NOR TO GREEN ENGINEERING COM- PANY, OF EAS'lIl CHICAGO, INDIANA, A CORPORATION OF ILLINOIS.

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Application led February 25, 1921. Serial No. 447,810.

To all whom t may concer/n.:

Be it known that I, THOMAS A. MARSH, a citizen of the United States, residin at `Chicago, in the county of Cook and tate v of Illinois, have invented new and useful Improvements in Furnaces, of which the following is a specification.

This invention relates to furnaces and more particularly-to those types of fu-rnaces y l0 wherein the fuel is`fed into and carried through the combustion chamber thereof on the progressive principle..

' In furnaces of the character referred to, and as generally constructed, the fuel is fed "i5 into the furnace and caused to be carried through the combustion chamber thereof in a' layer and to be discharged from the grate surface after the fuel has been consumed and served the purpose desired. It is among the objects 4of my invention to provide means for drawing heated'gases from the combustion chamber of the furnace down and -through the layer of green or fresh fuel as it enters the combustion chamber, so as to have a drying elfect on the same and remove all possible moisture therefrom and thereby stimulate ignition of the fuel as it enters the furnace.. By my invention I am enabled t0 gain a substantially uniform ignition of the fuel asl it enters the combustion chamber,

regardless of the depth of the fuel Alayer at such point, and lfurther to gain such effect on substantially all grades of fuel, whether of the slowly igniting quality or not. More- .55 over, with my invention, I lessen the possibility of the lowermost strata of the fuel layer failing to ignite during its travel through the combustion chamber and being discharged from the furnace with the ash and the like.

The invention consists further in the matters hereinafter described and more particularly pointed out in the appended claims.

In the accompanying drawings- Figure 1 is a longitudinal vertical sectional view of a furnace of the progressive feed type and havin@ applied thereto means constructed in accor ance with and serving to accomplish the objects of my invention;

Fig. 2 is a fragmentary vertical sectional view taken on line 2 of Figurel; and Fig.. 3'is a fragmentary vertical sectional view taken on line 3 of Figure 1.

The type of furnace structure illustrated in the accompanying drawings comprises, generally, a front wall 10, arear wall 11, a top wall 12, a bottom wall 13, and two side walls 14, all of which are suitably connected and serve to form an enclosed chamber, in which are located, among the usual appurtenances, the water tubes 15 and a grate 16, the latter being of the progressive feed character. In the instance shown', the grate 16 is of the endless chain type and 1s provided with front and rearsprocket wheels 17, 17, suitably secured to the required shafting and over which are trained connected links of the chain grate, so as to form an upper la a, 'upon which is supported the fuel bed in a layer, and a lower lap b. Any suitable formof mechanism may be provided for actuating the chain grate in a manner known in `this art. The grate extends into the combustion chamber or fire boX 18 through the front wall 10 and is suitably supported therein -above the bottom wall 13. In front of the front wall. 10 is a fuel hopper 19, which opens at its lower -end into the furnaceand above the grate through a. suitable opening fresh or green fuel into the furnace from` the lower end of the hopper 19 includes one or more reciprocating plungers 2O and a plurality of coking plates 21, 21, arranged at an inclination, as shown, and being oscillated in any well known manner. Extending inwardly from the front wall 10 at a suitable distance, above the supporting surface a of the grate is a fire arch 22, of any desired construction. f

In progressive feed types of furnaces, wherein the" fuel is conducted through the combustion chamber or fire boX in a layer, such as in furnace structures of the chain grate type, the ignition effected on the surface of the fuel'layer adjacent to its entrance into the furnace is essentially and primarily due'- to the heat radiated from the arch 22 thereabove, but asa general rule Athe particles of fuel remote from the surof fuel of a low heating value or `Which are' Y hard to ignite, such as high ash coals and -lignites and possibly also withsuch fuels as coke breeze and anthracite coal, both of lwhich are hard to ignite, there `is a prob-V ability of .parts of the fuelbed not being ignited and therefore failing to function throughout the entire path of travel through `the furnace. It is one of the primary objects of my invention to overcomethese difficulties and effect a uniform ignitioncf the fuel layer throughout its depth at its,4 entranceinto the combustion chamber, re'

gardless ofthedepth of the layer and of the kind of ffuelfy-being used. To accomplish this ,result :under all practical conditions,y

I provide a construction that will' permit the drawing'of heated gases from the combustion chamber down and through the layer of 4fuel as it enters said chamber and thereby 4:serve to remove the moisture with i which practically all fuel is loaded to some extent. .Incther words, I intendto effect a sort of "a pre-drying operation on the layer of fuel at its initial entrance into the fire box vand thereby stimulate the ignition of the fuel as itventers the furnace. To accomplish this I'have shown inthe drawings one form of my device, and in the example illustrated, I locatebeneath the upper layerl c of the chain grate a conduit or box23 extending across the front of the furnace adjacent the place where' the green or fresh 4the furnace, and such layer of fuel is dried fuel is fed into the combustion chamber 18. Said box or conduit 23 is suitably supported, preferably at its ends, in the side walls 14, 14: of the furnace structure. Said conduit 23 is closed on all sides except its top, and thereby open upwardly toward the upper layer (t of the chain grate, "as is clearly shown in Fig. 2. One end of said conduit 2P) communicates with and opens into a pipe 2l extending through the side wall lllkv of the furnace, as shown in Fig. 2. Said pipe 24- is, in turn, connected with a pipe 25, which opens at its upper or outer end into a pipe 2G serving to carry off the gases and products of combustion from the furnace into the chimney or stack 27. If found necessary, I' may provide a suitable damper 2S in the pipe 25 between its ends, so' as to regulate t-he upward flow of gas through said pi'p e. By reason of theconstruction just described, the -pipe 25 and connected conduit or box 23 are placed under suction bythe draft in the pipe 26, with the result that some of the 'heated gases in the combustion chamber 18 beneath the arch 22 are drawn downward and through the layer of fuel entering the furnace and carried to the stack through the Abox 23 and the Connected pipes 24 and 25. In Figs. 1 and 2. the arrows c indicate the manner in which the. heatedgases are drawnl through the fuel i maarre the grate 16. ldanifestly, the layer of fuel vbeing' fed into the furnace is dried and the moisture removed therefrom by the heatedy gases being drawn down'andthro'ugh the .full depth of the layer, the result being thatthe ;,fuel will ignite more readily by reason of ,the heat radiated by the arch and lalso by coming into contact with the particles already are. To 4facilitate further drying of the layer of fuel as it enters the furnace, I may also 'provide beneathv the coking plates 21 a conduit or box 29, like wise extending across the furnace and suit ably supported at its ends in the side walls thereof, as shown for instance in Fig. 3.

Said .box 29 isalso Vclosed on all sides, ex-

cept beneath the coking` lates, and thereby opens upwardly througi the opening between the coking plates 21, as shownin Fig.A

1, and is provide at one end with a pipe 30 lextending through the side wall 14 of thelfurnace. Said pipe 30 is connected with by having its moisture removed by such heatedgases being drawn through the fuel layer. The conduit 29, like the conduit 23,

is placed.` under suction by the draft createdv in the flow of gases or products of combustion through the pipe 26 to the chimney, as previously described. In Figs, 1 and 3, the arrows l serve to indicate the manner in which the heated gases are drawn through the fuel layerand into the suction box 29 layer) and into the suction box 23 beneath y beneath the Acoking plates. In the type of furnace structure illustrated, the portion of the fuel bed beyond the suction box 23 may be placed under forced draft so as to force air upwardly through the upper layerl of the grate and the layer of fuel `carried thereon, or such portion of the .fuel may be subjected to natural draft, as the case may be, as indicated by the arrows e in Fig. 1. But at any-rate, by" the construction described there. is,provided means for subjecting a portion` .per section of the fuel on the grate to suction downward through .the fuel bed so asvto dry the layer of fuel on such portion or-section of the grate,`

while the air for complete combustion on the other 4portion of the grate is drawn or forced upward through such portion of the fuel bed. While I have shown my invention as being' applied to a type of furnace megeve wherein the fuel is fed into the same by means of an endless chain grate, yet it is of course understood that my invention may be appliedto furnaces having other types of mechanism for feedingand progressing a layer of fuel therethrough. Moreover, `'I have shown the conduits or suction boxes 23 and 29 both being placed under suction by the draft created in the flow of the gases or products of combustion from the furnace into the chimney or stack, yet it is of course understood that said conduits or boxes may be placed under suction by mechanical means if desired.

The objects of my invention will be apparent to those skilled in the art, but it will be readily noted that the fuel being fed into the furnace, no matter what the degree of ignition may be, will be predried to such an extent that the ignition of the fuel layer will take place through the full depth of the layer and thereby gain the greatest efficiency by having all particles of the fuel ignited and serving the duties intended, instead of allowing the lowermost strata of the layer to remain unignited and be wasted by being discharged with the ash. As previously set forth, there are many grades of fuel which are of such a loW volatile character as to render ignition rather slow .underA conditions other than when the layer of fuel being admitted to the furnace is placed under suction so as to draw heated gases through it for the purposes herein stated.

In the accompanying claims I have used the term combustion chamber, and it is to be of course understood that by such term I mean the entirespace into Which the fuel is fed and including the space beneath the fire arch, as well as the space beyond the same.

Although I have shown and described in detail herein one form of device embodying the features of my invention, yet it is of course to be understood that the several details of construction and arrangement of parts illustrated may be variously changed` and modified without departing from the spirit and scope of my invention, and I do not wish to be restricted to the details of construction and arrangement of parts shown except as pointed out in the appended claims.

I claim as my invention:

1. In a furnace having a combustion chamber` the combination of a progressive feed grate therein, inclined means for feeding fresh fuel on said grate, said means having an opening therein, a conduit located beneath said inclined means and opening upward toward the same, and means for placing said conduit under suction for drawing heated gases from the combustion chamber downward and through the fresh fuel as it is fed over said inclined means.

2, In a furnace having a combustion chamber, the combination of a progressive feed grate therein, means for feeding fresh fuel on said grate at the front end thereof, said means including rockably mounted inclined coking plates above said grate, a

conduit located beneath said ,plates and opening upward toward the same, and means for placing said conduit under suction for drawing heated gases from the combustion chamber downward and through the fresh fuel passing over said plates.

3. In a furnace having a combustion chamber, the' combination of a progressive feed grate therein, means for feeding fresh fuel on said grate at the front end thereof,

said means including rockably mounted inel clined coking platesv above -said grate, two conduits, one located under the coking plates and the otherbeneath the gra-te adjacent said plates, said conduits opening upward toward the plates and grate, respectively, means for placing said conduits under suction for drawing heated gases from the combustion chamber downward and through the fresh fuel while fed on said grate.

In testimony that I claim the foregoing as my invention, I affix my signature this 19 day` of February, A. D. 1921.

THOMAS A. MAR-SH. 

